The invention concerns cosmetic compositions for the treatment of hair or skin, having a content of new, macromolecular compounds derived from chitosan, which are employed in a suitable cosmetic base.
The invention further concerns new N-hydroxypropyl-chitosans, as well as processes for the production thereof.
It is already known to employ cationic polymers, in particular polymers which display quaternary ammonium groups, as conditioning agent in cosmetic compositions, particularly for the treatment of hair. Based upon a reciprocal action between their ammonium groups and the anionic groups of the hair, the cationic polymers possess a great affinity towards keratin fibers.
It has been found out that the employment of such cation-active polymers in such cosmetic compositions provides numerous advantages: the disentanglement of the hair, as well as its treatment, are facilitated, and, moreover, the hair is provided with elasticity and lustrous effect. On account of their affinity towards keratin, however, these polymers tend to accumulate in the hair upon repeated use, so that the hair becomes heavier, which is undersirable as a final effect.
Moreover, synthetic polymers provide problems on account of the physiological activity of possibly present trace monomers, which are removable from the polymers only with difficulty.
It has already been attempted to eliminate the above-mentioned disadvantages by employing in such cosmetic compositions the water-soluble salts of chitosan, i.e. polyglucosamines producable from chitin by means of deacetylation. In this connection, reference is made to European Pat. No. 0 002 506, as well as German Pat. No. 26 27 419.
In the same manner as with the plurality of cation-active polymers having quaternary groupings, chitosan likewise frequently provides the disadvantage that it is not too compatible with the anion-active surface-active agents which in customary manner find use in cosmetic compositions for the treatment of hair, particularly in shampoos. It is therefore necessary to apply the chitosan for penetration in separate treatments, namely before and/or after the shampooing.
In addition, the chitosan displays, in neutral and alkaline medium, near insolubility, so that its use, for example, in alkaline permanent shaping compositions or hair dyeing compositions is not possible.
By means of employment of glycidyl chitosans instead of chitosan salts according to DE-OS No. 32 23 423, the above-mentioned disadvantages can be avoided. The reaction of chitosan with glycide is, however, very cost-intensive, since glycide is a more expensive raw material, not produced on a large scale.